We have been trying to extract RNA from fixed skin samples. We take a skin
biopsy, put it immediately in 4% paraformaldehyde in PBS, fix for 6 hours
then homgenize and use the TriZol method to extract RNA. The best we got
was a very faint band of low MW (probably snRNA), but no trace of rRNA. The
RNA can't be degraded because when we fix this way and do in situ hyb., we
get a signal, so there is intact RNA left in the skin sample. Maybe fixed
cells don't brake open in TriZol and only a fraction of the small molecules
diffuse out.
Question: Does anybody have experience with RNA extraction from fixed
samples?
Freezing the samples in liquid nitrogen is not an alternative.
Thank you
Sami